"My engine started making a rattling sound and I checked it with my stetescope type thing. It is the water pump. I read in a manual that it has a weep hole, and that once it starts leaking it is time to change the pump. Should I just replace it now, or wait."
Water pumps typically need to be replaced because EITHER the seal goes bad, and coolant leaks out the weep hole, OR the bearing begins to fail. If your water pump is making noise, the bearing is going bad, and you need to replace it now. There is no good way to predict how long it will continue to run.
When antifriction bearings (either ball or roller type) begin to fail, typically it is due to fatigue. The surface metal on the ball/roller and race is continuously going through stress reversals. If you look at a point on the surface of the race, each time a roller goes over under load, it compresses. When the roller passes, the compression is released. If you look at a point on the roller, the same thing is happening. Ultimately, the surface metal fatigues and begins to spall off. This can either be from the rollers or race. Of course other things can lead to the failure of antifriction bearings, like lack of lubrication, but water pumps have sealed bearings, so this is probably not the problem. Even if it is, there is no option for relubing.
The life of a given antifriction bearing depends on speed and load. This is why you don't want to have the belt excessively tight. It adds load to the bearing and will reduce its life.
By the way, a bearing which is beginning to fail can allow the shaft to wallow around and ultimately also lead to seal failure. It can also ultimately lock down completely.
Anyway, my suggestion is to change it now while it can be scheduled, rather than waiting and having it totally fail at an inopportune time.
From: Earl Zwickey
You have to remove both the right tire and the flexible skirting to get at the lower water pump bolts. When removing the rubber skirting I ran into a problem where one of the retainers wouldn't come out. It was the philips screw - expanding type. I had to just rip it out with a pair of long nose pliers - not that this is difficult. But you can't just pop down to the hardware store to pick up a replacement. I also had to remove the battery side cover to be able to fit a socket/torque wrench along side the water pump. The job was done in an evening - probably around 3-4 hours of work. The biggest pain was the fiberglass insulation between the body and the engine. Wear a long sleeved shirt or you will be feeling the fiberglass for a day or so later!
From: Joe Perkowski